In carrying out hemming with a hem folding attachment, it has hitherto been the general practice to feed cloth while guiding it in a sewing direction by supporting the cloth with the left hand and bending the end of the cloth into an S-letter form along its hem with fingers of the right hand before it enters the hem folding attachment. However, such an operation required special skill, which does not allow everyone to carry out hemming easily.
U.S. Pat. No. 3,786,768 discloses an apparatus furnished with an apparatus for prefolding the hem prior to its entry into a hem folding attachment. Said apparatus is applicable only to hemming of a tubular workpiece, or in other words an endless hem such as that on a skirt. It is designed to have a tubular workpiece placed on the apparatus and to then circulate it once to form an S-letter shaped fold for the hem, followed by driving of the sewing machine to circulate once more the workpiece to effect hemming. According to this patent, it is necessary to form first an S-letter shaped prefold all along the hem. Accordingly, it is not possible to carry out hemming while simultaneously feeding the cloth into the apparatus and bending it into an S-form. According to said apparatus, folding the hem into an S-letter form is also made by pushing the edge portion of the cloth toward the center of the cloth. However, as shown in FIG. 15, as the edge portion of the cloth is pushed in, the edge of the cloth comes to shift gradually toward the center of the cloth, so that the edge of the cloth is deviated toward the left of the lower folding edge E of the cloth and the product value is reduced.